Method of grinding scraper blades



May 7, 1957 s. v. RuM-scHwENsEN 2,791,073

- min-10D 10F GRINDING SCRAPER BLADES 7 Original Filed Nov. 5, 1953 2Sheets-Sheet 1 g sh INVENTOR. M: l m-vs/mg GkuM-S'cuwe/vxu M y 1957 s.v. GRUM-SCHWENSEN 2,791,073

answer: 01-" GRINDING SCRAPER BLADES Original Filed Nov. 5, 1953 2Sheets-Sheet 2 m m m United States Patent 6 METHOD F GRINDING SCRAPERBLADES Sofas Valdemar Grum-Schwensen, Alleroed, Denmark Originalapplication November 5, H53, Serial No. 390,337. Divided and thisapplication December 2d, 1954, Serial No. 478,245

2 Claims. (Cl. 51-285) This invention relates to an improved method ofgrinding scraper blades having at least one edge surface to be ground,and this application is a division of my copending application, SerialNo. 390,337, filed November 5, 1953.

Amongst the requirements for such grinding methods the most important isthat the finished blades have sharp cutting edges without nicks or thelike, and when a grinding device is used, operation of this grindingdevice must be so simple that a single man without special training cancomplete the grinding of so great a number of scraper blades per timeunit that the use of the device is profitable.

In the only hitherto known grinding devices for scraper blades eachscraper blade is first set-up in a blade holder or carrier, one edgesurface is ground, the blade is then inverted in the carrier and theopposite edge surface is ground. After this, the blade has to be set-upin another part of the grinding device where the side faces of the bladeare ground one by one in order to take off burrs formed by the grindingof the edge surfaces, and this latter setting-up necessitates thus twomore operations. Owing to these many operations the grinding of scraperblades becomes altogether so complicated a matter that most often bladesare ground by hand after the same method as used in the device stated.

Further, either the grinding of a scraper blade takes place in agrinding device of the type hitherto used or by hand, very often thescraper blade can only be used a comparatively short time beforeregrinding is necessary.

An object of this invention is to provide a method of grinding scraperblades which will enable them to stay sharp for a long period of time.

Another object of this invention is to provide a method of grindingscraper blades which makes it possible in a single operation and in asimple manner to obtain sharp cutting edges without nicks or the like atleast at one edge surface of a scraper blade.

A further object of this invention is to provide a method of grindingscraper blades having at least one edge surface to be ground, by whichseveral times in succession the scraper blade is ground alternately bymeans of an edge surface grinding tool on the edge surface and by meansof at least two side face grinding members on each side face of thescraper blade at the side edges of the edge surface. By this method isattained partly that the work of setting-up the scraper blades issubstantially diminished, and partly that the grinding itself isimproved because the alternate grinding of the edge surface and the sidefaces will produce a sharper and more even cutting edge than it hithertohas been possible to produce by the hitherto used grinding methods.

With these and other objects in view, the invention resides in the novelmethod and the novel features of construction as more fully hereinafterset forth.

In the accompanying drawings forming a part of this specification and inwhich like numerals are employed to designate like parts throughout thesame.

Figs. 1 to 3 show schematically and in perspective views the principleof the invention in three different embodiments of the invention, and

Fig. 4 shows an embodiment of a grinding machine operating on theprinciple according to Fig. 1.

Referring to Fig. 1, a scraper blade indicated by 1 is placed with itsedge surface adjacent the surface of an edge surface grinding tool 3formed as the surface of a cylinder rotatable on its axis 4. Owing tothe rotation of this cylinder 3 the edge surface 2 of the scraper blade1 is ground when the scraper blade is pressed against the grinding tool3. To avoid wear of the grinding tool 3 along the same part thereof,either the grinding tool 3 or the scraper blade 1 must be axiallydisplaceable as indicated by arrows 5 as regards the scraper blade 1.Somewhat above the grinding cylinder 3 and on either side of the scraperblade a stationary side face grinding member 6 is arranged and ispressed against the side faces of the scraper blades. When the scraperblade 1 has been ground for some time along its edge surface 2, it israised by hand or by means of members not disclosed in this figure, sothat it is displaced such a distance above the cylinder 3 that the sidefaces adjacent the edge surface lie between the grinding surfaces ofgrinding members 6' and are ground for taking off the burrs which wereformed during the grinding of the edge surface. When the scraper bladehas been ground a short while in this position, it is again moveddownagainst the cylindrical grinding tool 3 for renewed grinding of the edgesurface, and several times in succession these operations are alternateduntil the grinding operation is completed. After this, the scraper bladeis inverted and the opposite edge surface is treated in the same manner.

In the type of device disclosed in Fig. 2 there is likewise used acylindrical edge surface grinding tool 3, and the scraper blade is alsoin this instance reciprocated parallel to the cylinder axis 4. Thesurface of cylinder 3 is provided with a number of annular grooves 7,each of which is engaged by two side face grinding members 6 in such amanner that there is one grinding member 6 on either side of the scraperblade with its grinding surface abutting the side faces of the scraperblade 1 adjacent the edge surface 2. By means of this construction it isnot necessary to raise the scraper blade 1 from the cylindrical grindingmember 3, because grinding of parts of the edge surface takes placesimultaneously with grinding of parts of the side faces at other partsof the edge surface, so that every part of the edge surface of thescraper blade is ground several times in succession alternately alongthe edge surface and along the side faces. In this manner ofconstruction, however, the grinding members 6 are subjected to unevenwear and therefore often have to be trued up. In the embodiment shown inFigs. 1 and 2 as well as in the embodiments described hereinafter, thegrinding members 6 are preferably pressed against the scraper blade bymeans of springs 6a.

In the type of device illustrated in Fig. 3 the scraper blade 1 lieswith its edge surface 2 on an edge surface grinding tool 8 shaped as afiat disc which rotates in the direction indicated by an arrow 9. Theshaft 10 of this grinding disc is jcurnalicd in the one end of an arm11, the other end 12 of which is journalled to oscillate on a stationaryshaft (not shown). The arm 11 may, as indicated by arrows l3, perform areciprocating oscillation so that the greater part of the grindingsurface of disc 8 may contact the edge surface 2 of the scraper blade,and thus distribute wear of the disc surface. Also in this instancethere is arranged, somewhat above the surface of the grinding disc 8, agrinding member 6 on either side of the scraper blade 1 abutting theside faces thereof, and these grinding members are, as in every casewhen the scraper blade is raised from the grinding disc 8 to a positionin which the side faces adjacent the edge surface are opposite thegrinding surfaces of the grinding members 6, reciprocated parallel tothe scraper blade for grinding the side faces adjacent theedge surface2.

An embodiment of a grinding device according to the principle indicatedin Fig. 1 is shown partly schematically and in perspective view in Fig.4. This device is provided with a cylindrical edge surface grinding tool3 mounted on a shaft 4 rotatably journalled in bearings 42 and 43. Abovethe grinding tool 3 is arranged a scraper blade carrier or holder 44 inwhich a scraper blade 1 may be clamped by means of a clamp screw 45.

The carrier44 is by means of leaf springs 46 connected to supportingmember 47 attached to a driving rod 48. This rod is rotatably journalledand longitudinally displaceable in stationary bearings 49 and 50disposed on a frame or support only shown by symbols. The end of rod 48at the left-hand side of Fig. 4 is engaged for limited rotation in abushing 51 attached to the one end of a connection rod 52, the other endof which is attached to a crank 53 attached to a driving shaft 54rotatably journalled in the frame. This shaft 54 is rotated by anyappropriate means (not shown) in the direction indicated by an arrow 55,thus imparting to the driving rod 48 a reciprocal motion in its bearings49 and 511.

To the driving rod 48 is attached a pin 56 carrying a roller 57 disposedopposite an elongated abutment member 53. This member 58 has such alength that it may engage the roller 57 irrespective of the displacementof the driving rod 48. The abutment member 58 is mounted on the upperend of a rod 59, the lower end of t which is oscillatorily journalled inbearings 60, 60 in the frame, the rod being further provided with twolaterally extending arms 61 and 62. The one arm 61 is acted upon by apressure spring 63 which continuously endeavours to hold the abutmentmember 58 against the abutment roller 57. The other arm 62 lies over acam disc 64 attached to a shaft 65 rotatably journalled in the frame.The rotation of shaft 65 produced in a manner described later, causesthe arm 62 to engage an eccentric portion of a cam disc 64 to the effectthat the abutment member 58 is thrust away from the abutment roller 57.This eccentric portion of cam disc 64 is so shaped that the abutmentmember 58 only engages the abutment roller 57 a short time during eachrotation performed by the cam disc.

When abutment member 58 engages abutment 57, the driving rod 48 isoscillated in such a manner that the supporting member 47 swingsupwardly, thus raising the scraper blade from the grinding tool 3. Thisoscillation is so great that the edges of the lower edge surface 2 ofthe scraper blade 1, after the blade is swung away from the grindingtool 3, is raised between side face grinding members 6 positioned ashort distance above the grinding tool 3 and displaceable towards theside faces of the scraper blade, against which they are held resilientlyby means of a spring 66. There are two grinding members 6 on either sideof the scraper blade in the embodiment illustrated, but the table or thelike support in which they are supported and the means for holding themin position and guiding them are not shown.

The means for operating grinding tool 3 and cam disc 64 comprise a worm67 mounted on shaft 54 and engaging a worm wheel 68 attached to atubular shaft 69 rotatably journalled on shaft 4. This tubular shaftcarries furthermore a gear wheel 70 meshing with another 4 gear wheel 71which has a few more teeth than gear Wheel 70. Gear wheel 71 is attachedto shaft and thus operates cam disc 64. Shaft 65 carries furthermore agear wheel 72 having a few teeth less than gear wheel 71 and meshing agear wheel 73 on shaft 4, so that this gear wheel 73 operates the shaft4.

Thus, this gearing causes partly that the grinding tool 3 and the camdisc 64 are rotated at a speed considerably slower than the rotationalspeed of the driving shaft 54, and consequently slower then thereciprocations of the driving rod 48, and partly that cam disc 64 isrotated at a speed different, but not much different, from the speed ofthe grinding tool 3. The result of this is that the scraper blade 1 israised from the edge surface grinding tool 3 and again moved to contactthis member at parts thereof which differ for each rotation performed bythe grinding tool 3. In this manner is attained that the wear on thegrinding tool is evenly distributed along its entire surface.

As it is important that the oscillations performed by the scraper bladeabout the axis of rod 48 always are of proper value, it is possibleforcibly to move abutment member 58 away from abutment roller 57irrespective of the position of cum disc 64. The means may e. g. asshown consistof a pull wire 61:; connected to arm 61. Thus, when ascraper blade 1 is to be inserted in position, it is possible to makesure that the scraper blade carrier 44 is always in the same position inrelation to grinding tool 3, which position is determined by the meansfor limiting the oscillations of the driving rod 48 in relation to thebushing 51. The scraper blade 1 can thus always be inserted in exactlythe same position.

The grinding tool 3, in the embodiment shown in Fig. 4, is provided witha number of annular grooves '74, which have been found to produce a moreuniform grinding and less wear than would be the case if these grooveswere omitted.

What I claim is:

1. The method of mechanically grinding the edge of a tool blade whichconsists in reciprocating the blade in its own plane in one directioninto and out of contact with a moving abrasive surface and betweenopposed abrasive surfaces yieldingly contacting the opposite blade facescontiguous to the ground edge and at the same time effecting a relativereciprocation of the blade in its own plane and the three abrasivesurfaces in a direction trans verse to the first-mentionedreciprocation.

2. The method of mechanically grinding theedge of a tool blade whichconsists in simultaneously reciprocating the blade in its own plane indirections transverse to each other into and out of contact with arotating abrasive surface and between opposed abrasive surfacesyieldingly contacting the opposite blade faces contiguous to the groundedge.

References Cited in the file of this patent UNITED STATES PATENTS417,615 Webster Dec. 17, 1889 1,054,006 Lentz Feb. 25, 1913 1,116,557Brightman Nov. 10, 1914 1,190,718 Brunsell et a1. July 1], 19161,457,845 Lochhead June 5, 1923 1,581,919 Case Apr. 20, 1926 1,594,246Dechert July 27, 1926 1,915,477 Sheehan June 27, 1933 2,161,115 WalstromJune 6, 1939

